I am a grad in a three-field department, but I did my undergrad in a four-field, and I miss it. When you hit grad, other than a mandatory survey course in the other sub-fields, you really don't take courses outside your immediate discipline. I found myself taking courses in the linguistics department because officially I'm a cultural but most of my previous work included linguistic. We have no interaction with the students in the other sub-fields, and that's a tough one. We bonded as first-years, and then we never saw the others again. It's almost like they don't exist. I think if I'd known we didn't do interaction with the others I might have gone somewhere else to school, actually.